Odd Transparency or Normal Issues
You're experiencing a sorting problem due to Alpha Blend. Changing the Blend Mode to Alpha Hashed in the material properties should fix this issue. If you have to use Alpha Blend make sure that Show Backside is disabled.

Sorting Problem
When writing to the color buffer using transparent blend modes, the order in which the color blending happens is important as it can change the final output color. As of now Eevee does not support per-fragment (pixel) sorting or per-triangle sorting. Only per-object sorting is available and is automatically done on all transparent surfaces based on object origin.